A Model-Based Soft Sensor to Avoid Explosions in Direct Heaters Due to Skin Point Threshold Overtaking

Abstract

A model-based method, called SkinHBTpassi, to estimate skin temperature in direct flame heater is given.

The knowledge of skin temperatures in a direct flame heater is very important for a mechanical guarantee about heater pipes which could undergo to a thermal stress (or even a thermal shock) with the consequence of a probable failure.

A common practice is to put some thermocouples for skin temperature monitoring along the direct fired face of heater pipes. But also a good practice is to be able to estimate skin temperatures by the simple knowledge of flows and flow temperatures.

This new method, through a quiet complex computation of the view factors between pipes and flames, is able to estimate the heat flux pattern into the radiative part of the oven. The method is neither a shortcut nor a very detailed one.